Modern guideway transportation systems typically utilize Automatic Train Control Systems (ATCS) that feed various data to automatic control systems on-board the trains. Data is provided to controllers located on-board the trains and includes both direct control data used to control the actions of the respective trains and communication data used to communicate system-related information relative to the overall transportation system.
At various times during the operation of the ATCS, the on-board controller of a given train might fail. For example, a failure of a controller might include an event related to the hardware or software of the system that prevents the on-board controller from performing Automatic Train Operation (ATO) or Automatic Train Protection (ATP) functions.
The ATP functionality ensures safe train movement. For instance, ATP is designed into an ATC system to prevent rear-end, head-on, and sideswipe collisions due to conflicting train movements; passenger hazards due to unscheduled door openings; and damage or collisions caused by improper guideway switch movements/settings, or trains exceeding the allowed civil limit, or commanded, speeds.
ATO performs required non-vital functions such as speed regulation, programmed stopping, door control and performance level regulation. ATO commands are always subordinate to the ATP subsystem supervision. The ATO subsystem of the ATC system is primarily designed to provide regulation command of the train speed within the limits imposed by the ATP subsystem and to provide train movement within the passenger ride quality criteria as established by operating policy. Additionally, the ATO subsystem controls station dwell-time control, i.e., the amount of time any given train is permitted to stand idle at a station; on-board station arrival display control; and train audio announcement control.
In most, if not all, conventional ATC systems, once a failure occurs with respect to the on-board controller, it is necessary to dispatch a maintenance crew to the failed train to reset the failed controller. Manual intervention of this nature requires a significant amount of time, including time to detect the failure, time for the maintenance crew to travel to the guideway station closest to the train with the failed controller, time for the crew to travel on the guideway from the station to the disabled train and time for the crew to actually reset the controller and place the train in an operable condition. This process can take anywhere from approximately 40 minutes, or more, on average to recover a failed train.
Furthermore, after the controller is reset, the train must be manually driven until its relative position within the overall transportation system is established and automatic operation and control of the train can resume. Accordingly, failed on-board controllers result in delays and operational mode changes in addition to the penalties associated with these delays and changes. The penalties include passenger frustration and the hazards associated with passengers navigating the guideway, e.g., if passengers disembark the train prior to the train arriving at a station.
One solution to the above-mentioned problems is proposed in U.S. Pat. No. 4,023,753 to Dobler. In Dobler, a control system for controlling driverless vehicles on a fixed guideway is disclosed. One of the safety features in the Dobler system is a so-called operations monitor alarm (OMA). The OMA protects the system against abnormal operation and provides a signal to warn of abnormality. Once activated, the OMA brings instruction execution to a steady halt and changes the system safe signal to the unsafe condition. According to Dobler, the OMA can be cleared by auto-restart or by manually pressing the system reset switch at the computer console. If the OMA is cleared by the system reset switch, the program must be restarted manually.
The Dobler system, however, still suffers from some of the same problems mentioned above in regard to other conventional systems. For example, the Dobler system still requires that the train be manually driven to establish the train's relative position within the transportation system.